A baby with an armoured brain

Dense calcification and even ossification of a chronic subdural hematoma is rare but has been well documented.1 When extensive, it has been likened to a shell or carapace, encasing the brain, thus the term "armoured brain."2 The frequency with which radiologically demonstrable calcification occurs within the membranes of a chronic subdural hematoma has been reported to range from 0.3% to 2.7%.3 However, Harwood-Nash4 recorded a 10% incidence among children with chronic subdural hematomas studied by plain radiographs. Although usually seen in subdural hematomas resulting from trauma, it has also been reported in post-meningitic subdural effusions as well as subdural hematomas associated with ventricular shunting.5 The latter condition may occur because of a partial collapse of the brain when the intraventricular pressure is reduced by the shunt; this collapse results in widening of the subdural space and stretching of the bridging veins, which thereby increases the risk of hemorrhage.4 Although calcification of subdural hematomas seems more common in children, it has been reported in all age groups.1 The interval between the occurrence of the hematoma and the development of the calcification varies from 6 months to many years.1,5 Our patient had a normal CT scan at age 4 months; however, bilateral calcification was evident 6 months later.